buildman: Fix the 'help' test to use the correct path

When buildman is run via a symlink, this test fails. Fix it to work the same
way as buildman itself.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/buildman/func_test.py

@@ -180,7 +180,7 @@ class TestFunctional(unittest.TestCase):
         self._base_dir = tempfile.mkdtemp()
         self._git_dir = os.path.join(self._base_dir, 'src')
         self._buildman_pathname = sys.argv[0]
-        self._buildman_dir = os.path.dirname(sys.argv[0])
+        self._buildman_dir = os.path.dirname(os.path.realpath(sys.argv[0]))
         command.test_result = self._HandleCommand
         self.setupToolchains()
         self._toolchains.Add('arm-gcc', test=False)